The present invention is a system and method for controlling load division in multiple generator systems. More specifically the system utilizes digital signal processing to control load division.
Power systems with independent power supply units must be able to meet the highest load demands of the power system. To have the required capacity large power systems typically use multiple power generators arranged in parallel rather than one large generator. When using this method, the most efficient energy distribution occurs when the power supplied by each generator is equal. Variations in wiring, excitation characteristics and speed control mechanisms of the generators can cause the load on the generators to become unequal. Unequal loading creates unnecessary heat and mechanical wear on the generators, and results in inefficient operation and reduced reliability on heavily loaded generators. A control circuit is used to counter these problems and maintain even loading among the generators.
In order to equally distribute the power, known parallel power systems use a system of dedicated current transformers and breaker auxiliary contacts wired together to form a current transformer loop (CT loop). The CT loop generates a difference from average (DFA) current signal for each generator channel. Based upon the DFA current signal, further analog circuitry is used to determine the real and reactive components of the current for each generator channel. Once the real and reactive currents are found, the load division between the generators can be controlled. As long as the voltage of each generator is constant across all parallel channels, current alone is a reasonable parameter to use to control power. However, the current transformers require additional circuitry and hardware to determine the DFA and extract the real and reactive components of the current. The additional circuitry and hardware reduces the accuracy of the load division, adds expense and complexity, and reduces the system reliability. Also, impedance in the external current transformer loops can increase measurement error.
Thus, a system that eliminates the need for dedicated current transformers, and associated wiring, hardware, and circuitry is needed.